|Year : 2010 | Volume
| Issue : 4 | Page : 174-176
Radiation exposure profile and dose estimates to flyers Enroute Frankfurt to Mumbai
DD Rao1, AG Hegde2
1 Environmental Survey Laboratory, TAPS Colony, TAPP(Post), Thane(Dt.), India
2 Health Physics Division, Bhabha Atomic Research Centre, Trombay, India
|Date of Web Publication||1-Dec-2011|
D D Rao
Environmental Survey Laboratory, TAPS Colony, TAPP(Post), Thane(Dt.)
Source of Support: None, Conflict of Interest: None
Cosmic ray produced gamma dose rates recorded by continuous dose logging systems shipped in a commercial flight flying in Frankfurt-Dubai-Mumbai sector are presented. The doses measured, in the 10 hour flight duration, at 10 minute interval were analyzed and a gamma dose rate factor of 1.14 μSv/h of flying was evaluated. The gamma dose rates were in the range of 0.74 to 1.34 μSv/h in the flight path.
Keywords: Cosmic radiation, air crew, radiation exposure, frequent fliers
|How to cite this article:|
Rao D D, Hegde A G. Radiation exposure profile and dose estimates to flyers Enroute Frankfurt to Mumbai. Radiat Prot Environ 2010;33:174-6
|How to cite this URL:|
Rao D D, Hegde A G. Radiation exposure profile and dose estimates to flyers Enroute Frankfurt to Mumbai. Radiat Prot Environ [serial online] 2010 [cited 2020 Mar 29];33:174-6. Available from: http://www.rpe.org.in/text.asp?2010/33/4/174/90454
| 1. Introduction|| |
The earth is continuously bombarded by the high energy radiation (galactic radiation) from solar system commonly known as cosmic radiation. Intensity of cosmic ray radiation exposures change with altitude, and increases rapidly with the increase in altitude from the earth. The background radiation levels are generated by the cosmic rays consisting of energetic protons, alpha particles and heavy nuclei of natural elements interacting with atmospheric constituents through atomic and nuclear collisions. Passenger and cargo flights fly at different altitudes and therefore the crew and passengers are exposed to radiation levels of about 100-200 times higher than the average background levels on the earth at sea level.
Estimates of potential radiation exposures of air crew and frequent travelers in United States of America, Canada and Europe indicate that these groups receive exposures above the effective dose limits of general public (Townsend, 2001). A typical commercial jet aircraft fly at an altitude of 30,000-40,000 feet (9-12 km) and at these heights radiation exposure rates increase significantly. Switzerland and other European countries have guidelines and suggestions on radiation exposure to air crew members in sectors that may potentially expose them to levels exceeding 1 mSv per year. (StSV, 1994). The suggestions include: i) inform the crew members at the time of first flying on the radiation exposure levels while flying, ii) assess the effective dose to individual crew members using computer predictions and route sectors, when doses expected are less than 4 mSv/y, iii) estimate the effective dose to individual crew members by monitoring with appropriate devices when doses are expected to exceed 6 mSv/y. UNSCEAR (1993) reports an annual average effective dose to air crew as 3 mSv/y. The paper details the radiation exposure profile recorded with date and time stamping during the flight from Frankfurt to Mumbai and evaluation of average radiation exposure received by the flyers and air crew members.
| 2. Materials and Methods|| |
Six numbers of Gamma Tracers (continuous gamma dose monitoring systems) were procured in the year 2001 from M/s Genitron, Germany. They were shipped by the passenger air craft from Frankfurt airport on 25/01/2009 and arrived at Mumbai airport on 26/01/2009. The monitors being shipped in fully operational condition, have recorded the ambient gamma dose rates generated from cosmic ray interaction with atmospheric components at high altitudes, presumably at altitudes of about 8-10 km. Gamma Tracer (GT) units contain complete measuring electronics including power supply, lithium battery (2 x 3.6 V) and are placed in a hermetically sealed weather tight casing. Capacity of batteries is such that they can be used for about five years without replacement of battery and in fact the probes are still working even after 8 years of continuous operation. GTs are equipped with two independent GM detectors of type 70003A having gamma sensitivity of 2.6 impulses/s per mSv/h. It records the dose rates of two GM tubes independently along with date and time stamping. The RAM has a capacity to store 12800 data records and when all memory is used up the oldest data points will be deleted from memory. Dose rate data recording was fixed at an interval of 10 minutes from among several of the cycles such as 1, 2, 5, 10, 15, 30, 60 and 120 minutes. GTs are equipped with a temperature sensor and have measuring range of -40 o to 70 o C. Communication with GTs, data transfer and data analysis is carried out using Gamma View (GVIEW) Software. GTs can store the data of 3 months period at a cycle time of 10 minutes. Data analysis was carried out to evaluate the average dose rate per hour at high altitude and also the total exposure received by the passengers and air crew during their flight in Frankfurt-Dubai-Mumbai sector.
| 3. Results and Discussions|| |
[Table 1] gives the gamma dose rate record of the passenger flight from Frankfurt to Mumbai via Dubai. [Figure 1]. shows the graphical record of the dose rates. Although six gamma tracers were procured, the data record of only one tracer is presented in this paper. It was also observed that the dose rate profiles of other five GTs placed in a cardboard package were replicas of [Figure 1]. The flight took off from the airport at 22.40 hrs on 25-01-2001 and landed at Dubai on 26-01-2001 at 04.20 h. After halting at Dubai for about 2.5 h, the flight took off to Mumbai on 26-01-2001 at 06.00 h and landed at Mumbai at 08.00 h. The dose rate data from 25-01-2001, 20.00 hrs to 25-01-2001, 22.40 h is taken as the background radiation level at the airport of Frankfurt. The dose rate data from 26-01-2001, 04:20 hrs to 26-01-2001, 06:40h is taken as the background radiation level at the airport of Dubai.
|Table 1: Gamma dose rate profile during the flight of Frankfurt-Dubai-Mumbai sector|
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3.1 Flight path of Frankfurt to Dubai
The average background gamma dose rate was 61.2 nSv/h with standard deviation of 5.61 nSv/h. The range of gamma dose rate during the flight path was 900 nSv/h and 1332 nSv/h, presumably, at a height of around 8-10 km from the earth. The integrated gamma dose exposure, above the background, to the passengers and the flight crew was 5494 nSv (5.5 μSv) during the flying of 5 hours 20 minutes.
3.2 Flight path of Dubai to Mumbai
The average background gamma dose rate was 44.2 nSv/h with standard deviation of 7.09 nSv/h. The range of gamma dose rate during the flight path was 738 nSv/h and 1148 nSv/h, presumably at a height of around 8-10 km from the earth. The integrated gamma dose exposure, above the background, to the passengers and the flight crew was 1732 nSv (1.73 μSv) during the flying of 2 hours.
The total gamma dose during the entire sector flying was 7226 nSv (7.2 μSv) in 7 hours 20 minutes. The average gamma dose rate, including background, at an altitude of 8-10 km was 1135 nSv/h with the standard deviation of 114. The effective radiation doses in some of the international sectors for comparison are as follows (Bailey, 2000).
Assuming a flying gamma dose rate of ~1.0 μSv/h, a passenger flying for 10 hours would receive a net exposure of 10 μSv, which is approximately equivalent to the effective dose received by the member of public at 1.6 km fence post of a nuclear power station in India. Pilots and air crew members flying about 2000 hours per annum (40 hours x 50 weeks) would be exposed to about 2 mSv per annum of gamma dose, which is twice that of the dose limit for the member of public. Similarly, frequent travelers would also be exposed to same kind of doses as that of pilots due to the cosmic ray produced radiation while flying.
| 4. Conclusions|| |
The Gamma dose rate profiles of 10 minute interval recorded in a passenger flight of Frankfurt-Dubai-Mumbai sector are discussed. The net gamma dose received by the passengers and crew members during flight was about 7.23 Sv in the air time of 7 hours 20 minutes. The passengers and air crew members would receive a gamma dose rate of approximately 1.14 μSv/h at an altitude of about 8-10 km from the earth in this sector. About 1000 flying hours would expose the traveler or pilot of about 1 mSv gamma dose which is the dose limit for member of public residing near a nuclear power station.
| 5. Acknowledgements|| |
Authors wish to thank Shri H.S. Kushwaha, Director, HS&EG, BARC and Dr. P.K. Sarkar, Head, HPD, BARC for their constant encouragement in carrying out investigations.
| 6. References|| |
- Bailey Susan, (2000), Air Crew radiation exposure- An overview, Nuclear News, Jan, 32-40.
- StSV, (1994), Strahlenschutzverordnurg, 22, SR 814.501.
- Townsend L.W., (2001), Radiation exposures of air crew in high altitude flight, Journal of Radiation Protection, Vol. 21, 5-8.
- UNSCEAR Report -1993, Sources ad effects of ionizing radiation, 1993.